Quantification of Airborne Fungal Spores Comparing Molecular Tracers via Ion Chromatography and UV-LIF Method

Fungal spores represent an understudied subcategory of bioaerosols that can impact human health as pathogenic and allergenic particles. Fungal spores also have been shown to act as effective ice nuclei and giant cloud condensation nuclei in some cases. This has implications on the hydrological cycle on local and regional scales by impacting the formation and evolution of clouds and precipitation. The quantification of fungal spores has been limited in the past due to methods that were costly and that suffered from poor time resolution. The most commonly applied methods for airborne fungal spore analysis have traditionally included microscopy and culturing, which can undercount the atmospheric fungal concentration by an order of magnitude. New techniques utilizing molecular tracers have allowed for the estimated contribution of fungal spores to atmospheric aerosols via ion chromatography. Additionally, the development of ultraviolet- laser/light induced fluorescence (UV-LIF) instruments for bioaerosol detection has added the element of real-time, size-resolved analysis to the methods for fungal spore quantification. Here, UV-LIF and ion chromatographic techniques are explored for the estimation of atmospheric fungal spore concentrations. Results from the BEACHON-RoMBAS campaign show that the two techniques provided atmospheric fungal spore concentrations with 13% on one another. Additionally, fungal tracers increased 3 fold during rainy periods in comparison to dry periods consistent with the increase of atmospheric fungal spores during times of increased relative humidity. Application of a thresholding scheme suggested by Savage et al. (2017) eliminated lowly fluorescent particles and reduced R2 values between non correlated variables during the INIUT-BACCHUS- ACTRIS campaign.